Rechargeable lithium ion batteries, also known as secondary lithium ion batteries are desirable as power sources for a wide range of applications. Their desirability stems from their relative high energy density. For some current commercial batteries, the negative electrode material can be graphite, and the positive electrode material can comprise, for example, lithium cobalt oxide (LiCoO2), LiMn2O4, having a spinel structure, or LiFePO4, having an olivine structure.
The capacities of secondary lithium ion batteries have been greatly improved with the development of high capacity lithium rich metal oxides for use as positive electrode active materials. For some important applications, such as vehicle application, it is desired that secondary lithium ion batteries be able to charge and recharge for many cycles without a great loss of performance. Lithium ion batteries generally can be designed in particular for high energy power output with high current capabilities or high power output with moderate current capabilities. With either type of design, it is desirable for the average voltage and capacity to fade slowly with cycling such that power and energy output correspondingly changes slowly with cycling.